Bipolar plate

Abstract

A bipolar plate has a multi-layered structure including an inner metallic layer and at least one outer metallic, corrosion-resistant layer splatted, embedded, diffused and interlocked into the inner metallic layer.

1 - 20 . (canceled)  
   
   
       21 . A bipolar plate, comprising: 
 a metal substrate; and,    a dense metallic corrosion-resistant layer formed by impinging a plurality of metallic particles onto a surface of the metal substrate at high velocities such that the impinged metallic particles metallurgically interlock with the metal substrate.    
   
   
       22 . The bipolar plate of  claim 21 , wherein the metallic particles are selected from the group consisting of nickel-based alloys, chromium-based alloys and carbide-based alloys and a combination thereof.  
   
   
       23 . The bipolar plate of  claim 22 , wherein the carbide-based alloys constitute a major part of the combination of nickel-based, chromium-based alloys and carbide-based alloys.  
   
   
       24 . The bipolar plate of  claim 22 , wherein the dense corrosion-resistant layer is about 0.008-0.010 inch thick.  
   
   
       25 . The bipolar plate of  claim 21 , wherein the metal substrate is made from metal having a low electrical resistance.  
   
   
       26 . The bipolar plate of  claim 25 , wherein the metal substrate is selected from the group consisting of aluminum, stainless steel, aluminum alloys, zinc, zinc alloys, magnesium, magnesium alloys and a combination of these.  
   
   
       27 . The bipolar plate of  claim 21 , wherein the metal substrate has opposite sides, and wherein each of the opposite sides comprises the dense metallic corrosion-resistant layer and an active region including a plurality gas conveying channels.  
   
   
       28 . The bipolar plate of  claim 27 , wherein the gas conveying channels each have a V-shaped cross-section.  
   
   
       29 . The bipolar plate of  claim 28 , wherein the gas conveying channels of one of the opposite sides of the metal substrate guide a flow of oxygen gas and extend vertically between horizontally extending conduits in the active region of the one of the opposite sides so that water formed as a byproduct is drained under gravity.  
   
   
       30 . The bipolar plate of  claim 29 , wherein the gas conveying channels of the other side of the metal substrate guide a flow of hydrogen gas and are arranged in a horizontal zig-zag configuration.  
   
   
       31 . The bipolar plate of  claim 28 , wherein each of the channels comprises at least one projection blocking the channel fully or partially, and wherein the at least one projection is configured to redirect gas flow toward a membrane that is disposed between opposing sides of adjacent bipolar plates.  
   
   
       32 . A method of producing a metallic bipolar plate comprising the steps of: 
 providing a plurality of metallic particles with high kinetic energy, the metallic particles being selected from metals or metal alloys exhibiting anti-corrosion characteristics;    impinging the highly energized metallic particles against a surface of a metal substrate at high velocities, thereby flattening, embedding, diffusing, and interlocking the metallic particles with the metal substrate, thereby forming a dense metallic corrosion-resistant layer metallurgically interlocked with the metal substrate.    
   
   
       33 . The method of  claim 32 , wherein the dense corrosion resistant metallic layer is provided by using a thermal spray technique or a cold gas dynamic technique.  
   
   
       34 . The method of  claim 31  further comprising the step of 
 reducing a temperature gradient across the bipolar plate by heating a face of the metallic substrate opposite to the face treated to form the dense corrosion-resistant layer.    
   
   
       35 . The method of  claim 34  further comprising the step of reducing the temperature gradient by simultaneously forming the corrosion-resistant metallic layer on opposite faces of the metallic substrate, the dense metallic substrate being made from metal having a low electrical resistance selected from the group consisting of aluminum, cast iron, steel, aluminum, aluminum alloys, zinc, magnesium, magnesium alloys and a combination of these.  
   
   
       36 . The method of  claim 32 , wherein the metallic particles are selected from the group consisting of nickel-based alloys, chrome-based alloys, carbide-based alloys and a combination thereof.  
   
   
       37 . The method of  claim 36 , wherein the combination of the nickel-based alloys, chrome-based alloys and carbide-based alloys are predominantly carbide-based alloys.  
   
   
       38 . The method of  claim 32 , wherein the dense corrosion-resistant metallic layer is about 0.008-0.010 inch thick.  
   
   
       39 . The method of  claim 32  further comprising the step of forming a plurality gas conveying channels within a boundary region of the metallic substrate.  
   
   
       40 . The method of  claim 39 , wherein the gas conveying channels each have a V-shaped cross-section, the method further comprising the steps of arranging the gas conveying channels on a face of the metal substrate to guide oxygen in a vertical direction, thereby evacuating water from the corresponding dense corrosion-resistant metallic layer under gravity, and arranging the gas conveying channels on an opposite face of the metal substrate to guide hydrogen in a horizontal zig-zag configuration, and providing obstructions in each of the gas conveying channels.